Stygofauna are aquatic animals that live in groundwater.
Globally, stygofauna are found in many different types of groundwater environments including fresh and saline aquifers, caves in limestone, and within the smaller pore spaces, voids, cracks and fissures in virtually any other type of rock or sediment, including springs and sediments in the beds of streams and rivers.
Most stygofauna are invertebrates, predominantly species of crustaceans, but also including worms, snails, water mites, and diving beetles, while others are vertebrates (fish).
Some species of stygofauna are specially adapted to underground life, and are typically blind and pale with elongated appendages to help them navigate in complete darkness. These obligate aquatic subterranean species are termed stygobites.
Stygofauna are found in every Australian state and territory, but is especially rich in Australia’s arid regions where groundwater provides an important refuge from arid surface conditions.
Within the last two decades, scientific research and biological surveys, often associated with surveys for the purpose of environmental impact assessment of mining and other projects, have greatly increased knowledge about West Australian stygofauna; this State is now known to be a world hotspot for such organisms. Surveys in other Australian states have also revealed diverse and abundant stygofauna.
A recent review estimated 2,680 species of stygofauna in the Western half of the Australian continent.
Stygofauna are important because they:
- Comprise an inconspicuous but important component of World biodiversity
- Contribute ecosystem services via nutrient cycling and as indicators of groundwater health
- Represent outstanding examples of adaptation and ongoing evolutionary processes
- Contain many ancient lineages of high scientific value and conservation significance
- Have many species with small distribution ranges, i.e. Short Range Endemics (SRE’s)
- Are vulnerable to extinction from environmental changes and human impacts.
- Include species and communities that are protected under state and commonwealth environmental legislation
- Need to be considered as a factor in environmental assessment and approval for development projects in most Australian states and territories